Network operators providing PVC services to the customers using the SPVx features had the following problems.
a. On destination node failures the SPVx on the originating node have to be reconfigured to the alternate destination. [Manual user intervention was required, upon the detection of the destination failure.]
b. To provide network service guarantees to the PVC customer, the network operator had to configure shadow connections from the source node to the alternate destination node.
Destination SPVx resiliency protects the originating SPVx connections upon the destination node failures [fabric level, portcard/port level as well as system level failures]. When multiple attempts to setup a SPVx connection fails with one of the user pre-configured failure codes the SPVx call will be automatically redirected to the alternate destination specified by the user.
Nortel Networks, Inc. supports two features that have similarity with the present invention.
1. SVC call redirection feature allows multiple (up to seven) X.121/E.164 alternate addresses to be specified. If a call attempt to a destination fails, the alternate destinations will be tried automatically.
2. The second feature is called SVC hunt group. A single X.121/E.164 address serves multiple end devices. Calls are automatically distributed between the multiple end devices, depending on the end device resource availability.
Some of the differentiating factors of the present invention are,
When there is a failure on the active SPVx connection the destination detects the failure and releases the SPVx call with switchover information in the release message to trigger a redirection to an alternate destination.
The present invention does not simply redirect all the calls that fail to the alternate destination. Instead, the user can configure the failure codes that should trigger a redirection. If three attempts to setup a call fails with one of the specified failure codes, the call automatically gets redirected to the alternate destination.
After a redirection to the alternate destination has taken place, the source node periodically tries to restore the connection back to the primary destination and free up the resources on the secondary destination. In addition, these techniques are applicable to failures of connections, in general, whether they be on the source side, or anywhere between the source and the destination.